Lichtenberger



Aug. 18, 1959 H. LICHTENBERGER 2,899,917

CYCLONE FIRING Filed June 24, 1957 2 Sheets-Sheet l FIG. 1

INVENTORL Horsf Lichrenberger ATTORNEY 18, 1959 H. LICHTENBERGER 2,899,917

CYCLONE FIRING 2 Sheets-Sheet 2 Filed June 24, 1957 FIG.3

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JNVENTOR. Horsr Lichrenberger BY Z ATTORNEY CYCLONE FIRING Horst Lichtenberger, Wesel, Rhineland, Germany, as-

signor to The Babcock & Wilcox Company, New York, N.Y., a corporation of New Jersey Application June 24, 1957, Serial No. 667,364

6 Claims. (Cl. 110-28) This invention relates to a fluid heating unit, and more particularly, to a fluid heating unit fired by cyclone type furnaces, such as disclosed in US. Patent No. 2,594,312, discharging high velocity high temperature heating gases to a furnace chamber for flow therethrough to a convection heated fluid heating portion of the unit, with the furnace chamber so proportioned and arranged relative to the cyclone furnaces as to eifect a substantially uniform temperature and uniform transverse distribution of the gases flowing through the furnace chamber.

In a fluid heating unit having a vertically extending furnace chamber including opposed upright front and target or gas deflecting walls and receiving high temperature heating gases from cyclone furnaces arranged in the front wall thereof, it has been customary (l) to space and relatively arrange the front and target walls to provide a heating gas flow area substantially rectangular in horizontal cross-section, and (2) to arrange each cyclone furnace so that an imaginary vertical plane in cluding the major axis thereof extends substantially normal to the front and target walls. While satisfactory operation has been obtained over most of the load range with a unit so arranged, gas temperatures and gas distribution transversely of the furnace chamber and of the convection heated fluid heating section have been nonuniform at some loads, particularly in a situation where the unit is provided with a plurality of cyclone furnaces symmetrically arranged about the centerline of the furnace chamber and only one cyclone furnace is in operation for the lower loads. Though the conditions of non-uniform gas temperatures and gas distribution especially prevail in a unit provided with an even number of cyclone furnaces symmetrically arranged about the cen terline of the furnace chamber, these conditions also obtain at times in a unit having an uneven number of cyclone furnaces in circumstances involving shutdown of States Patent particular cyclone furnaces for reasons other than decreasing load. Such gas conditions result in a substantial decrease in the overall heat absorption, with consequent decrease in unit efficiency, and fouling of heating surfaces when aslag-forming solid fuel is fired.

In the present invention the furnace chamber of the fluid heating unit is specially proportioned and arranged relative to the cyclone furnaces to effect a substantially uniform temperature and transverse distribution of the gases flowing from the furnace chamber to the convection heating pass over substantially the entire load range and particularly when only one of the cyclone furnaces is in operation. More specifically, the invention is concerned with the provision of an improved construction of a fluid heating unit comprising a furnace chamber including a front wall on which are arranged a pair of cyclone furnaces and an upright target wall disposed opposite the gas outlets of the cyclone furnaces and arranged to receive the impact of the products of combustion discharging therefrom; with the front and target walls horizontally spaced and relatively arranged to provide a heating gas flow space decreasing in depth in a horizontal plane from the center toward the side walls of the furnace chamber; and with eachcyclone furnace arranged so that an imaginary vertical plane including the major axis thereof extends substantially normal to the front wall of the furnace chamber and at an obtuse angle to the target wall with reference to the side of the vertical plane facing the other cyclone furnace.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which certain specific embodiments of the invention are illustrated and described.

Of the drawings:

Fig. 1 is a sectional side elevation of a cyclone furnace fired fluid heating unit constructed in accordance with my invention;

Fig. 2 is a sectional plan view taken along the line 22 of Fig. l; and

Figs. 3 and 4 are sectional plan views of other forms of cyclone furnace fired fluid heating units constructed in accordance with my invention.

While various kinds of liquid and gaseous fuels can be burned in the cyclone furnace construction illustrated, the constructions illustrated and hereinafter described are specifically designed and particularly adapted for burning coarsely pulverized or granulated bituminous or semi-bituminous coal.

The main portions of the unit illustrated in Figs. 1 and 2 include a pair of independently operable cyclone furnaces 1i) and 12 arranged laterally adjacent and opening to a vertically extending furnace chamber 14 having a lower or gas receiving chamber section 16 and an upper or radiant chamber section 18, of which only a portion is shown, divided by an upright wall or target wall 20 and slag collecting screen 22. The furnace chamber 14 is defined in part by upwardly extending fluid cooled front 24, rear 26 and side walls 28 and by a floor 30.

The cyclone furnaces 10 and 12 are symmetrically disposed about the centerline of the furnace chamber 14 and arranged in the front wall 24 thereof at substantially the same elevation. Each of the cyclone furnaces comprises an elongated combustion chamber of substantially circular cross-section arranged with its major axis downwardly inclined toward the front wall 24 at a substantial angle to the horizontal and formed by closely spaced studded tubes 32. The tubes 32 are covered by a layer of suitable refractory material, proportioned for the maintenance of the refractory surface under .a normal mean temperature above the fuel ash fusion temperature, and connected at their opposite ends to headers 34 and 36 which, in turn, are suitably connected into the fluid circulation system of the unit. The front or outer end of each combustion chamber is formed with a frusto-conical extension. The rear or inner end of each combustion chamber has a fluid cooled wall formed by intermediate portions of the tubes lining the lower part of the front wall 24 and arranged substantially normal to the major axis of the combustion chamber. This combustion chamber end wall includes an inwardly projecting throat forming a gas outlet 38 flaring towards its discharge end and a slag outlet 40 for the discharge of molten slag when a slag-forming fuel is fired. Coarsely pulverized or granulated bituminous or semi-bituminous coal, carried in a stream of preheated primary air, is introduced into each cyclone furnace with a whirling motion by a burner 42 centrally located at the outer end thereof. Streams of secondary air are admitted tangentially through secondary air ports 44 along the length of each cyclone furnace in the same direction of rotation and at the outer side of the whirling burning primary air-fuel mixture. The molten slag resulting from combustion continuously discharges through the outlet 40 of each cyclone furnace and flows down to a slag pool on the floor 30 of the gas receiving section 16 of the furnace chamber, whence it is continuously drained through a slag tap opening 46 into a slag tank 48, along with ash and slag particles which may be separated in the gas receiving section of the furnace chamber. The gases discharging through each outlet 38 contain little, if any, combustible matter, combustion being substantially completed in the combustion chamber. Fly ash and molten particles present in suspension in the outgoing gases are largely removed in the lower portion of the furnace chamber 14.

All boundaries of the furnace chamber 14 are fluid cooled by means of fluid conducting tubes associated with the respective walls. The front wall 24 and the floor 30 are lined by tubes 50 having their lower ends connected to a drum 52 and their upper ends to a header 54. The rear wall 26 is lined by tubes 53 having their lower ends connected to the drum 52. Each side wall 28 is cooled by a row of tubes 55, some of which have their opposite ends connected to headers 56 and 58, and the remainder extending from the header 56 throughout the height of the furnace chamber.

The slag screen 22 and the target wall 20 are formed by tubes 60 extending between the lower drum 52 and the header 54. Intermediate portions of the tubes 60 are bent inwardly and downwardly from a position superjacent the cyclone furnaces to a position vertically spaced from the floor 30 and at substantially the elevation of the slag outlets 40 of the cyclone furnaces. These tube portions together with suitable refractory material close the top of the gas receiving section 16 of the furnace chamber and form the upright imperforate target wall 20 thereof.

In accordance with the present invention, the front and target walls 24 and 20 of the gas receiving section 16 of the furnace chamber are horizontally spaced and relatively arranged to provide a heating gas flow space decreasing in depth in a horizontal plane from the center toward the side walls 28; and each cyclone furnace is arranged so that an imaginary vertical plane including the major axis thereof extends substantially normal to the front wall 24 and at an obtuse angle to the target wall 20 with reference to the side of the vertical plane facing the other cyclone furnace.

In the embodiment of Fig. 2 the portion of the front wall 24 including the cyclone furnaces is substantially coplanar and the target wall 20 includes an intermediate outwardly projecting V-shaped portion 62 the gas deflecting sides 62A, 62B of which extend from the center of the furnace chamber to a position horizontally spaced from and beyond the boundary limits of the gas outlets 38 of the cyclone furnaces. The sides 62A, 62B are arranged so that an imaginary vertical plane including the major axis of each cyclone furnace intersects an intermediate part of a corresponding gas deflecting side at an obtuse angle with reference to the side of the vertical plane facing the other cyclone furnace and so that the gases from the corresponding cyclone furnace gas outlet will be deflected by the corresponding gas deflecting side before flowing to the slag screen 22. In the construction of Fig. 2 the aforesaid vertical plane extends substantially normal to the plane of the front wall 24. In the operation of the unit, the products of combustion from the cyclone furnaces discharge into .the gas receiving section 16 of the furnace chamber, are deflected by' the sides 62A, 62B of the target wall 20, pass downwardly while expanding laterally, and then pass' upwardly through the slag screen 22 and the radiant'chambe'r 18 to the con- 4 vection heated fluid heating portion of the unit, not shown.

In the modified construction shown in Fig. 3, the target wall 20 is substantially co-planar and the front Wall 24 includes an intermediate outwardly projecting truncated V-shaped portion 64, the-sides 64A, 64B of which extend from positions adjacent the centerline of the furnace chamber toward the side walls thereof. The sides 64A, 64B include the gas outlets 38 of the cyclone furnaces and are arranged so that an imaginary vertical plane including the major axis of each cyclone furnace extends substantially normal to the corresponding side 64A or 64B and at an obtuse angle to the target wall 20 with reference to the side of the vertical. plane facing the other cyclone furnace. In the operation of the unit of Fig. 3, the separate streams of high temperature heating gases discharging from the cyclone furnaces converge toward each other, impact on the target wall 20and pass downwardly while expanding laterally, and then flow upwardly through the slag screen 22 and the radiant chamber 18 to the convection heating pass, not shown.

The embodiment of the invention illustrated in Fig. 4 is the same as that shown in Fig. 3 except the front wall 24 on which the cyclone furnaces are arranged is formed 'in the shape of an outwardly projecting V the sides of which extend from the center to the sides of the furnace chambert All of the constructions illustrated and described insure a more uniform temperature and transverse distribution of the gases leaving the gas receiving section of the furnace chamber and throughout the other gas passes of the unit, thereby promoting optimum unit heat absorption and efiiciency. These constructions are particularly advantageous in enhancing uniform transverse gas temperatures and gas distribution at low loads when, usually, only one cyclone furnace is in operation.

While in accordance with the provision of the statutes I have illustrated and described herein a specific form of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of other features.

What is claimed is:

1. A fluid heating unit comprising upwardly extending fluid cooled walls, including front and side walls, defining a furnace chamber, a pair of cyclone furnaces of substantially circular cross-section disposed on opposite sides of the centerline of said furnace chamber and arranged in the front wall thereof, each cyclone furnace having a gas outlet in one end thereof opening to said furnace chamber, said furnace chamber including upright wall portions opposite the gas outlets of the cyclone furnaces to receive the impact of the discharged heating gases, said front and upright walls being horizontally spaced and relatively arranged to provide a heating gas flow space decreasing in depth in a horizontal plane from the center toward the side walls of said furnacechamber, said cyclone furnaces being arranged so that imaginary vertical planes including the major axes thereof extend substantially normal to said front wall and at an obtuse angle to said upright wall portions with reference to the sides of said vertical planes facing each other, and means for introducing a combustible mixture into said cyclone furnaces for discharge through the respective gas outlets into impacting relation with said upright wall portions.

2. A fluid heating unit comprising upwardly extending fluid cooled walls, including front and side walls, defining a furnace chamber, a pair of cyclone furnaces of substantially circular cross-section disposed about the centerline of said furnace chamber and arranged in the front Wall thereof, each cyclone furnace having a gas outlet in one end thereof opening to said furnace chamber, said furnace chamber including an upright wall opposite the gas outlets of the cyclone furnaces to receive the impact of the discharged heating gases, said front and upright Walls being horizontally spaced and relatively arranged to provide a heating gas flow space descreasing in depth in a horizontal plane from the center toward the side walls of said furnace chamber, each cyclone furnace being arranged so that an imaginary vertical plane including the major axis thereof extends substantially normal to said front wall and at an obtuse angle to said upright wall with reference to the side of said vertical plane facing the other cyclone furnace, and means for introducing a combustible mixture into each cyclone furnace for discharge through its respective gas outlet into impacting relation with said upright wall.

3. A fluid heating unit comprising upwardly extending fluid cooled walls, including front and side walls, defining a furnace chamber, a pair of cyclone furnaces of substantially circular cross-section symmetrically disposed about the centerline of said furnace chamber and arranged in the front wall thereof at substantially the same elevation, each cyclone furnace having a gas outlet in one end thereof opening to said furnace chamber and arranged with its major axis inclined downwardly toward the gas outlet, said furnace chamber including an upright wall opposite the gas outlets of the cyclone furnaces to receive the impact of the discharged heating gases, said front and upright walls being horizontally spaced and relatively arranged to provide a heating gas flow space decreasing in depth in a horizontal plane from the center toward the side walls of said furnace chamber, each cyclone furnace being arranged so that an imaginary vertical plane including the major axis thereof extends substantially normal to said front wall and at an obtuse angle to said upright wall with reference to the side of said vertical plane facing the other cyclone furnace, and means for introducing a combustible mixture into each cyclone furnace for discharge through its respective gas outlet into impacting relation with said upright wall.

4. A fiuid heating unit comprising upwardly extending fluid cooled walls, including side walls and a co-planar front wall, defining a furnace chamber, a pair of cyclone furnaces of substantially circular cross-section symmetrically disposed about the centerline of said furnace chamber and arranged in the front wall thereof at substantially the same elevation, each cyclone furnace having a gas outlet in one end thereof opening to said furnace chamber and arranged with its major axis inclined downwardly toward the gas outlet, said furnace chamber including an upright wall opposite the gas outlets of the cyclone furnaces to receive the impact of the discharged heating gases, said upright wall including an outwardly projecting V-shaped portion the opposite sides of which extend from the center of said furnace chamber toward the side walls thereof, said front and upright walls being horizontally spaced and relatively arranged to provide a heating gas flow space decreasing in depth in a horizontal plane from the center toward the side walls of said furnace chamber, each cyclone furnace being arranged so that an imaginary vertical plane including the major axis thereof extends substantially normal to said front wall and at an obtuse angle to an intermediate part of a corresponding side of said upright wall V-shaped portion with reference to the side of said vertical plane facing the other cyclone furnace, and means for introducing a combustible mixture into each cyclone furnace for discharge through its respective gas outlet into impacting relation with said upright wall.

5. A fluid heating unit comprising upwardly extending fluid cooled walls, includnig front and side walls, defining a furnace chamber, said front wall including an outwardly projecting V-shaped portion the opposite sides of which extend from the center of said furnace chamber toward the side Walls thereof, a pair of cyclone furnaces of substantially circular cross-section disposed on opposite sides of the centerline of said furnace. chamber and arranged in the front wall thereof, each cyclone furnace having a gas outlet in one end thereof opening to said furnace chamber through a corresponding side of said V-shaped portion, said secondary furnace chamber including an upright co-planar wall opposite the gas outlets of the cyclone furnaces to receive the impact of the dis charged heating gases, said front and upright walls being horizontally spaced and relatively arranged to provide a heating gas flow space decreasing in depth in a horizontal plane from the center toward the side walls of said furnace chamber, each cyclone furnace being arranged so that an imaginary vertical plane including the major axis thereof extends substantially normal to the corresponding side of said front wall V-shaped portion and at an obtuse angle to said upright wall with reference to the side of said vertical plane facing the other cyclone furnace, and means for introducing a combustible mixture into each cyclone furnace for discharge through its respective gas outlet into impacting relation with said upright wall.

6. A fluid heating unit comprising upwardly extending fluid cooled walls, including front and side walls, defining a furnace chamber, said front wall including an outwardly projecting truncated V-shaped portion the opposide sides of which extend from positions adjacent the center of said furnace chamber toward the side walls thereof, a pair of cyclone furnaces of substantially circular crosssection symmetrically disposed about the centerline of said furnace chamber and arranged in the front wall thereof at substantially the same elevation, each cyclone furnace having a gas outlet in one end thereof opening to said furnace chamber through a corresponding side of said V-shaped portion and arranged with its major axis inclined downwardly toward the gas outlet, said furnace chamber including an upright co-planar wall opposite the gas outlets of the cyclone furnaces to receive the impact of the discharged heating gases, said front and upright walls being horizontally spaced and relatively arranged to provide a heating gas flow space decreasing in depth in a horizontal plane from the center toward the side walls of said furnace chamber, each cyclone furnace being arranged so that an imaginary vertical plane including the major axis thereof extends substantially normal to the corresponding side of said front wall V-shaped portion and at an obtuse angle to said upright wall with reference to the side of said vertical plane facing the other cyclone furnace, and means for introducing a combustible mixture into each cyclone furnace for discharge through its respective gas outlet into impacting relation with said upright wall.

References Cited in the file of this patent UNITED STATES PATENTS 1,351,977 Thomson Sept. 7, 1920 FOREIGN PATENTS 719,261 Great Britain Dec. 1, 1954 

